Abstract
1) Sodium lauryl sulfate (SLS) was hydrolysed in acidic solution at a high temperature, and the rate of hydrolysis was dependent on not only H+ concentration but also SLS. concentration. It was recognized that the rate of reaction was increased strikingly in the region of a certain concentration of SLS. 2) When the Critical micelle concentration (CMC) of SLS was determined by solubilization method with dye (Sudan III), it was approximately coincident with region of a certain concentration where the rate of reaction increased strikingly. 3) On the contrary to acidic solution, in alkaline solution, SLS above the CMC was a little more stable than that of below.